Art of radiocommunication



June 3, 1924. 1,496,155

F. J. FRANssoN ART OF RADTO COMMUNICATION Filed Nov. 8, 1919 wrmz'ss I?atented June 3, I924.

1 SITE PATENT OFFICE.

FRANS J. FRANSSON, OF SHORT HILLS, NEW JERSEY, ASSIGNOR T0 AMERICAN GASACCUMULATO'R COMPANY, OF ELIZABETH, NEW JERSEY, A. CORPORATION OF NEWJnnsny.

ART or RADIOC'OMMTIINICATION.

Application filedNovember 8, 1919. Serial No. 336,658.

To all whom it may concern:

Be itknownthat I, Fn-ANs J. FRANssoN, a subject of the King of Sweden,and a resident of Short Hills, in the county of Essex and- State of NewJersey, have invented an Improvement in the Art of Radiocommunication.of which the following is a specification.

This invention relates to the art of radio communication and moreparticularly to a duplex system of wireless telegraphy or telephony inwhich waves or messages may and received messages and, forbalancingpurposes, an absorbing circuit or dummy antenna is in someinstances coupled to the main antenna, such absorbing circuit being,however, very undesirable because it consumes considerable energy. Inother known duplex wireless systems, complicated and inefiicient meansare employed to avoid mutual interference in receiving and transmitting,both transmitting and receiving means in some of such systems beingcoupled to the loop antenna which latter is grounded.

The improved system embodying the present invention overcomes theundesirable features of the systems heretofore known and, in its broaderaspects, comprises a system of aero wires or an antenna means arrangedso as to include both a loop antenna and an open or plain antenna,whereby the desirable features of both types of antenna may bentilized.Both the loop antenna and the open antenna may have suitable variableinductance or capacitance or both in circuit therewith, for varying thereactance of the antenna and so arranged and balanced that theoscillations set up in the antenna means Will not interfere. Hence themessages or waves transmitted by the transmitting -me'ans coupled to theantenna means or to one branch thereof, will not interfere with" themessages or waves simultaneously re"- ceived by the receiving means thatiscoupled' to the antenna means or toits other branch, and vice versa.In this antenna system waves of the same or different wave length may bereceived and transmitted simultaneously without mutually interferingwith one another.

The above and otherobjects and the novel features of the inventionsherein disclosed will be apparent from the following descrip tion takenin connection with the figures of the accompanyingdrawing which forms apart of this application. It is to be underillustrate some of, the moredesirable embodiments of the broad underlying princi ples of thisinvention. but the invention is not confined to those systems hereindisclosed.

Moreover, the inventions herein disclosed are equally applicable toduplex systems of wireless telegraphy and wireless telephony, the properor well known transmitting and receiving apparatus in either case beingused.

In the drawing-'- Figure 1 is a diagram of a duplex radio system ofcommunication that embodies the present invention; and

Figures 2 to 6 inclusive are similar diagrams of modified-systems, eachembodying this invention;

Referring to Figures 1 and 2, the antenna or system of aero wires fortransmitting and receiving the waves to and from other'stationscomprises a combination of a loop or closed antenna A and an open orgrounded antenna- B. The antenna or oscillator means A and B may be ofany suitable construction to cooperate in the manner and for the purposedesired. The most desirable arrangement is one in which the loop orclosed antenna circuit A includes adjustable means such as variableinductance or variablecapacity or both and an open or grounded antennaportion 13* is provided with the usual coupling inductance coil andvariable condenser" for tuning or varying the wave length, such antennaportion B" being connected to the loop antenna circuit A in sucharelation that after the proper adjustment of the variable element orelements, a balanced condition will be obtained in which there willstood that the figures of this drawing merely be no flow of current fromthe loo-p antenna to the open antenna when the transmitting means iscoupled to the loop antenna, and in which the flow of current from theopen antenna to the loop antenna will be neutralized in the loopantenna, when the transmitting means is coupled to the open antenna. Theparticularly desirable loop antenna means A herein shown comprises thewires 10 and 12 connected to the ends of the wire 11, and respectivelyconnected to terminals of the variable condensers 13 and 14. The otherterminals of the condense s 13 and 14. may be connected together bysuitable inductance means, thereby completing the loop antenna circuitA. A particularly desirable form of connecting link between thecondensers 13 and 1 consists of two in dependently variable inductancesor coupling coils 15 and 16 respectively connected to the condensers 13and 14, and to each other at 17.

The open or grounded antenna means B may be of any suitable type thatwill cooperate with the loop antenna means A and the receiving and thetransmitting means in the manner and for the purpose desired. Theantenna B herein shown is a particularly desirable construction and consists of a variable inductance or coupling coil 18 that is connected bya conductor 19 to the common connection point 17 of the inductance coils15 and 16 of the loop antenna A. The inductance 18 is also connected tothe variable condenser 20 by a conductor 21, the said condenser beinggrounded, as at G.

By properly adjusting the various elements of the system to resonance,either a receiver R or a transmitter T may be used in or associated withthe loop portion A of the antenna in combination with a transmitter T ora receiver R in or associated with the open or ground portion B of theantenna, as indicated respectively in Figures 1 and 2. In the severalviews of the drawing the receiving means R and the transmitting means Tare, respectively,

only diagrammatically shown because any suitable or preferredtransmitting means adapted for wireless telegraphy or wireless telephonymay be employed that will properly supply the energy and produce thetelegraphic or telephonic waves desired to be transmitted. Likewise, anysuitable or preferred telegraphic or telephonic receiving means may beemployed that may be tuned to the incoming waves to properly receivethem telegraph or telephone messages.

In Fig. 1, for example, the inductance coil of the receiver R is shownas inductively coupled to or associated with the inductance coils 15 and16 of the loop antenna circuit A and the inductance coil of theneutralized and the transmitting apparatus transmitter T is shown asinductively coupled to or associated with the inductance coil 18 of thegrounded antenna circuit B. With the several variable elements adjustedfor resonance, the receiver R and transmitter T may operatesimultaneously to receive waves from other stations and transmit wavesto other stations without mutual interference. The currents induced bythe transmitter T in the inductance 18 will flow in equal and oppositedirections, through the inductances 15 and 16, and, accordingly,currents induced thereby in the inductance coil of the receiver R willbe 80 will therefore have no efiect upon the in dicating means of thereceiving apparatus.

The loop antenna circuit A is utilized for receiving purposes, the wavesgenerated at the distant station causing a current to flow or oscillatein the loop antenna and at a given instant such current will flow in thesame direction through the inductances 15 and 16, inducing currents inthe receiver inductance coil R to cause operation of the receivingapparatus.

In the arrangement shown in Figure 2, the inductance coil of thetransmitter T is inductively connected to or associated with theinductance coils 15 and 16, and when the various elements are properlyadjusted and balanced, none of the transmitted current or energy willflow to ground through the. inductance 18. and the receiving apparatus Rcoupled to the coil 18 will therefore not be affected in any way by thetransmitter. However, signals from other stations will be received onthe antenna system A, B, operating as an open antenna, whereby thereceiving apparatus will be operated by outside waves but not by thosegenerated by the associated transmitter. In this arrangement, theantenna inductance 18, the receiver inductance 22 and the. condenser 20are inclosed in a case 23 of con- 0 ducting material, which may begrounded as shown, and which is adapted to screen these parts of theP60611131 R from inductive influences of the transmitter T.

It will be understood that instead of inductively connecting or couplingthe trans mitter T to the loop antenna A, such transniitter may beconductively connected or coupled to such antenna, as shown for examplein Figure where the leads 25 and 26 of the transmitter are respectivelycon nected to the loop antenna A between the condenser 13 and inductance15 and between the condenser 14 and inductance 16.

In a system such as the present one it is also desirable to providemeans whereby the loop antenna circuit can be adjusted or balancedWithout changing the wave length at which it is desired to transmitsignals and to which the loop antenna has been tuned. W

In Figure 3, one way of accomplishing this purpose is shown, the sameconsisting in inductively connecting a short-circuited inductance 24 tothe inductances 15 and 16 in such a way that it can be moved axiallywith respect to the inductances 15 and 16. Otherwise the systemillustrated in Figure 3 is similar to the one illustrated in Figure 2.

Instead of inductively or conductively coupling or connecting thetransmitter to the loop antenna system, a capacitive cou pling may beused, which is found to be desirable when transmitting on short wavelengths. One arrangement of capacitive coupling is illustrated in Figure4 in which the loop antenna A includes condensers 27 and 28 substitutedin place of inductances 15 and 16 of the systems of Figures 1, 2 and 8.The leads 251, 261 of the transmitter are connected to the loop antennabetween such condensers 27, 28 and the condensers 131, 141,respectively, the latter being variable so that the loop antenna may bebalanced to prevent interference between the transmitter T and thereceiver R during their simultaneous operation. The open antenna branchcircuit '13 is connected to both condensers 27 and 28 at a point 171between said condensers, and otherwise the system of Figure 4 is ingeneral similar to those of Figures 2 and 3.

Figures 5 and 6 illustrate other duplex radio transmitting and receivingsystems wherein the loop antenna circuit may be adjusted or balancedwithout changing the wave length to which the loop antenna has beentuned. In Figure 5 the loop antenna circuit A includes two independentinductance coils 152, 162 between which is arranged a variable doublecondenser 30 of well known construction. The transmitter T has two coils31 and 32 which are connected in series and inductively coupled to thecoils 152 and 162. This arrangement is such that the loop antennacircuit is always balanced without changing the wave length, by means ofthe variable condenser 30, which has its movable plates connected toground by the open antenna circuit B through the inductance 18 andcondenser 20.

Figure-6 illustrates a system which is desirable when transmitting onshort wave lengths and the same is arranged so that the loop antennacircuit A may be ad justed without changing the wave length at which itis desired to transmit signals. In the system of Figure 6 the loopantenna circuitA contains a variable double condenser 33 of well knownconstruction that is connected to the condensers 133 and 1 13, which arealso in the loop antenna circuit. The leads 253, 263 of the transmitterT are connected to the loop antenna circuit A between the condensers133, 143 and the condenser 33, respectively. The movable plates of thedouble condenser 33 are connected to ground through the open antenna Band may be adjusted to a position to balance the loop antenna A fortransmitting purposes.

It will be obvious from the foregoing that numerous circuit arrangementsare possible which embody the broad principles of this invention, inwhich a simple and efficient radio system is provided for simultaneouslytransmitting and receiving waves or messages, without mutualinterference. Therefore, it is to be understood that the presentinvention is not limited to the systems shown and described in thepresent drawing and specification.

What is claimed is:

1. A system of radio communication'comprising the combination of antennameans having a loop antenna including condensers and a grounded antennaconnected to such loop antenna at a point between said condensers,transmitting means coupled to one of said antennas, and receiving meanscoupled to the other antenna.

2. A system of radio communication comprising in combination antennameans having a loop antenna including pairs of condensers, and agrounded antenna connected to such loop antenna at a point in balancedrelation to said pairs of condensers, transmitting means coupled to oneof said antenna means, and receiving means coupled to the other antennameans.

3. A system of radio communication comprising in combination antennameans including a loop antenna and a grounded antenna connected incircuit, transmitting means coupled to one of saidantennas, re* ceivingmeans coupled to the other antenna, and means for balancing said systemwithout changing the wave length adjustment at which it is desired totransmit signals.

In testimony that I claim the foregoing as my invention, I have hereuntosigned my name this 3d day of November A. D., 1919.

FRANS J. FRANSSON.

